Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quantos anos o prêmio Mercury Prize tem sido concedido?
 ###Tabelas: CREATE TABLE siena_college_research_institute_survey (siena_college_research_institute_survey_id AUTO_INCREMENT PRIMARY KEY, Seq. VARCHAR, Name VARCHAR, Background INT, Party Leadership INT, Communication Ability INT, Relations with Congress INT, Court Appointments INT, Handling of Economy INT, Luck INT, Ability to Compromise INT, Willing to take Risks INT, Executive Appointments INT, Overall Ability INT, Imagination INT, Domestic Accomplishments INT, Integrity INT, Executive Ability INT, Foreign Policy Accomplishments INT, Leadership Ability INT, Intelligence INT, Avoid Crucial Mistakes INT, Expert's View INT, Overall INT) CREATE TABLE whangarei (whangarei_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Years VARCHAR, Area VARCHAR, Authority VARCHAR, Decile VARCHAR, Roll VARCHAR) CREATE TABLE cast (cast_id AUTO_INCREMENT PRIMARY KEY, Character Name VARCHAR, Voice Actor (Japanese) VARCHAR, Voice Actor (English 1997 / Saban) VARCHAR, Voice Actor (English 1998 / Pioneer) VARCHAR, Voice Actor (English 2006 / FUNimation) VARCHAR) CREATE TABLE world_championship_group_b_slovenia (world_championship_group_b_slovenia_id AUTO_INCREMENT PRIMARY KEY, Games INT, Drawn INT, Lost INT, Points difference VARCHAR, Points INT) CREATE TABLE awards_and_nominations (awards_and_nominations_id AUTO_INCREMENT PRIMARY KEY, Year INT, Award VARCHAR, Category VARCHAR, Nominated Work VARCHAR, Result VARCHAR)  
SELECT COUNT Year FROM awards_and_nominations WHERE Award = mercury prize